I’m using OS X version 10.9.5, and Audacity version 2.4.2. When I plug in my microphone before and after opening Audacity, I don’t see it appear. I didn’t find anything to help in preferences, and it didn’t help to rescan audio devices. Would you please help me find out how to connect a microphone that isn’t my computer microphone?
Stereo speakers
Dual microphones
Headphone port
Support for Apple iPhone headset with remote and microphone
As far as I can tell your headphone port can not double as a microphone port.
Did you try going to System Preferences > Sound > Input to see if your microphone appears there? My guess is that it won’t. In that case you’ll need to find another way to connect your microphone, probably using a microphone-to-USB adapter.