A:Answer Unfortunately this is a limitation of those applications. Zoom and FaceTime only allow one source for microphone in and speaker out. So when you use a lightning microphone, unfortunately those applications do not give you the option to select the speaker on the phone as an output. This is a limitation of the app, and not this or any microphone.
I have been in discussions with Zoom to let them know that expended audio preferences for their mobile applications are a necessity, but unfortunately they have not added that functionality yet.
FaceTime is unlikely to add that functionality because they expect users to be using the iPhone's microphone and speaker.