In Silicon Valley, a place where the college-dropout startup founder—think Bill Gates, Steve Jobs or Mark Zuckerberg—is lionized, it is hard to stand out on account of precociousness or youth. But as she takes me on a tour of Binary Capital, the venture-capital firm where she is an analyst and an associate, Tiffany Zhong manages to.

That’s because Ms. Zhong, or Tiff as everyone calls her, is 18 years old.

Ms....