Unity microphone
https://forum.unity.com/threads/save-microphone-recording-to-disk.378038/
https://answers.unity.com/questions/354401/save-audio-to-a-file.html
Documents
https://docs.unity3d.com/ScriptReference/Microphone.Start.html
https://docs.unity3d.com/Manual/class-Microphone.html
Open Source Projects/Files:
https://gist.github.com/darktable/2317063