How to implement microphone emulation in C#?

Question

Programming

You need to implement microphone emulation in order to play sound files on its input.
In simple terms, you need a program that, when the user presses certain keys, plays music into the microphone, in order, for example, to turn on music to the interlocutor on Skype or in any game that supports voice chat.
How to implement this in C#?
I found the NAudio library, but I could not figure it out.