I think Cerebrus might just agree with me on this. I gave you what you need to know so far. It's obvious you haven't delved into the project completely yet, so I told you that you need to use Win32 APIs for communicating with hardware. How about going to Google and typing in "win32 api c# microphone" and see what comes up?
Heres what I got after about 10 seconds of browsing: http://www.codeproject.com/KB/audio-video/fister.aspx?df=100&forumid=1790&exp=0&select=1127305
