If you're facing targeted security threats, your problems run deeper than spyware on your devices. You need to check your physical spaces as well—your home, hotel room, office, and so on—for hidden cameras, mics, and other eavesdropping tools that someone may have planted. That means performing regular "technical surveillance counter measures" inspections. In other words? Checking for bugs.

"Hackers bug lots of places, including some people wouldn’t think of," says Jill Johnston, president of KJB Security Products, a security and surveillance device wholesaler. "Tanning beds, dressing rooms, bathrooms, hidden cameras in an Airbnb, on your car, in your house. You want to be able to scan a room and feel safe."

Look Around, Look Around

First, take a close look at your surroundings. Carefully check for anything new or out of place, and listen to your gut about whether anything seems off. You don't have to see the bug itself; installing eavesdropping devices can involve changes as subtle as shifting an object or a piece of furniture. A bug could be lodged in an inconspicuous object planted in plain sight, or it could be glued behind a small hole drilled in a wall.

Next, review the list of devices that are connected to your router for any that you don't recognize. Usually bugs that need internet connectivity will have a more clandestine plan for accessing the web, though, like using their own hotspot or SIM card, so also check the Wi-Fi networks with a strong signal available around you. Anything that's not coming from a neighbor or a nearby business, or other likely suspect, could be a bug's own network.

It's also important to think about a bug's power supply. Some may run on a battery, giving them a limited lifespan, but persistent surveillance requires a steady power source. Always follow visible wires, scan for wires in walls, and check outlets, crowded power strips, and extension cords. It's also worth considering what devices you have in the open that bugs could hide in to steal power. For example, this audio bug (complete with SIM card) hides in a USB to micro-USB cord, drawing power any time the cord is plugged in, while listening to everything around it.

Scantron

Once you've completed a thorough visual and physical inspection, you can use a variety of scanning tools to conduct a more advanced check. Truly spy-grade bugs often incorporate mechanisms to try to defeat scanners, so you'll have more success if you conduct multiple types of sweeps than if you rely on a one-size-fits-all approach.

"I tell everybody that calls, there’s no one device that I can sell you that will do everything," says Jon Marshall, president of the surveillance device seller Spy Gadgets.

Now turn off all wireless devices; not just laptops and smartphones but routers, set-top boxes, and that connected refrigerator that seemed like a good idea at the time. Then use a radiofrequency detector from a surveillance product seller—or even Amazon—to scan for transmitters by moving the instrument slowly and methodically around the space. You can also check your clothes and your bags for things like GPS-tracking bugs this way. Some devices show a visual graph of activity, while others make a sound that gets louder as you get closer to an RF-emitting source. Anything broadcasting a radio signal will pop up.

Commercial bugs usually fall in the 10 MHz to 8 MHz range, but some sweeping devices look at 10 hertz all the way to 24 GHz. Reliable instruments that can scan a broad RF range cost hundreds of dollars, but depending on your situation you could opt for cheaper models. Simple bugs can also create static or sound distortions as you turn the dial on a commercial AM/FM radio.