I just tried submitting my app and I got an email saying:
This app attempts to access privacy-sensitive data without a usage
description. The app's Info.plist must contain an
NSMicrophoneUsageDescription key with a string value explaining to the
user how the app uses this data.
Apple can see that there is code that accesses the microphone. There is no way that Apple can tell that during the run of your app, that code isn't actually accessed.
So you have two choices:
NSMicrophoneUsageDescriptionkey in Info.plist. The user will never see this as long as your app doesn't ever trigger the use of the microphone.