I heard Facebook hears your talks and gives u as recommendations when u speak about a thing frequently. I want to know if it still hears even if I have disabled microphone permission to the app?

Theoretically speaking: yes.
There exists an ultrasensitive sensor in every phone every app has access to. This sensor's data can be exploited to record audio while its original purpose is smth different.

That's as much as I know, I will have to check for good sources on that, though.

@bitteruhe Update: found the old news article I was referring to: https://wired.com/2014/08/...
I don't believe Facebook uses such methods. But who knows? Best idea is to delete Facebook