I know Facebook has said their app does not listen in using the phones microphone, but recently I have had reason to believe that.
1) was teaching my daughter to play chess. The phone was near by not being used. Just a couple of hours later I am on the Facebook app and magically ads for chess sets appear on my feed.
2) wife and I were discussing painting our house. I had mentioned how earlier in the day I was at Home Depot and saw Behr paints there, wife said she preferred sherwin Williams. Low and behold magical valley her Facebook and mine too feeds had adds for Behr paints.
I have deleted the app and now use browser to access.