One of the people familiar with his move said that Oberfest will look into opportunities for Apple in the medication adherence space, meaning helping people take their medicines on time. When people don't take their meds, that costs the U.S. health care system between $100 to $289 billion a year. For that reason, a lot of start-ups are focusing on finding ways to help people adhere to their prescriptions.

Mango Health is an app for people to track their medications, which is especially helpful for patients with chronic disease who take multiple medications. The company also offers incentives, such as gift cards, for users who take their tracked medications properly and on time.

Jason Oberfest, formerly the CEO of Mango Health , has joined Apple's health team.

But it's also possible that Oberfest's experience would fit into Apple's existing initiatives, including its Apple Watch, which is focused on behavior change, and is health software services, like HealthKit and ResearchKit.

Mango president Yadin Shemmer was promoted to chief executive officer in November. Oberfest updated his LinkedIn profile with his new role this week.

Apple declined to comment on the hire. Oberfest also didn't share what he would be working on at Apple.

Oberfest's background spans health care and technology. Prior to starting Mango Health, which is backed by Kleiner Perkins and Express Scripts, a public company in the pharmacy benefits space, he worked in gaming and social media. Oberfest was a senior vice president at MySpace, before joining a mobile gaming company called ngmoco.

Mango Health has raised just over $8 million in venture capital since it was launched in 2012.