I do not. However, I've heard it anecdotally many times. You can definitely find similar stories on reddit.
I'm guessing Facebook is doing some pretty complicated work to find that interest and serve the ad, but as evil as Facebook is I doubt they're straight up lying about using the microphone to listen and serve ads.
Facebook might obtain the ad profile match from a third party which obtained microphone access and would let them bot claim 'at this one company we do not use microphone recordings to target ads'
I'm guessing Facebook is doing some pretty complicated work to find that interest and serve the ad, but as evil as Facebook is I doubt they're straight up lying about using the microphone to listen and serve ads.