This is the feature in which Facebook “can tell who you are and what you've recently purchased,” she says. ... “Maybe you're in an airport, lingering in front of an ad, and that signals to an advertiser that you might be interested in the product.

Does Facebook spy on your conversations?

Rumors that Facebook listens to you through your phone's microphone have persisted over recent years. Facebook denies that it uses your microphone to eavesdrop or target ads to you. If you prefer, you can disable Facebook's access to your phone's microphone in Settings.

How do I stop Facebook from spying on me?