Can't figure out how Google did this. But when you use GBoard (Google's custom keyboard), they have dictation function inside and if you use it, keyboard open GBoard app which listening (because custom keyboards have no access to microphone) and after listening it goes back to previous app where did you call dictation function from. How is it possible? It works even with empty app build from template so I'm pretty sure it isnt working over some framework like FB Links etc.
Any ideas? Private API?