Nasty FaceTime bug could allow others to eavesdrop on your microphone or camera
https://techcrunch.com/2019/01/28/nasty-facetime-bug-could-allows-others-to-eavesdrop-on-your-microphone-or-camera/
You might want to turn off FaceTime for a few days.
A newly discovered bug in iOS allows FaceTime callers to listen in before you accept the call.