Go into your phone’s application settings and you’ll see a whole list of what an app like Facebook has access to: your camera, your location, your contacts, and, yes, your microphone too.
How about this for a warning? By downloading Facebook you give the app “permission to record audio at any time without your confirmation.”
Tom’s Guide security editor Paul Wagenseil says Facebook can pick up sound in the background. Facebook claims it uses that background audio for advertising only.