On the other hand, facebook can check (at least on IOS) easily if the device is jailbroken and behave differently.
You can also patch binary and inject some code, (probably swizzle AVAudioRecorder methods) for the same effect.
In this case, Facebook can check binary integrity, and change behavior accordingly.
So this is kind a cat and mouse game.
I'm not 100% sure what's involved in jailbreaking iOS, but I'm pretty sure on a rooted Android you could put measures in place to "fake" results for any root checks the Facebook app would run. You could patch any APIs Facebook could use to make such checks.
It is a bit of a cat and mouse game, but as the long history of software cracking shows, as long as they still own the machine, the crackers always have the upper hand.
But if they decide to do, I think best way of action will be some defensive programming around it, with plausible deniability.
I am guessing they are already checking binary integrity etc, also they can probably push code updates from server. So when you put this pieces together, they have everything they need technically.