Separating mic from computer audio

My microphone plugs in through an aux cord. When I plug it in through either the front panel or the mic port on the back it comes through as “Microphone (Realtek High Definition Audio)”. This channel also includes my desktop audio so everyone can hear my desktop audio in the call. Is there any way to separate my microphone audio from my desktop audio so the people in the call can only hear my microphone? I’m using it for discord but would love a blanket fix if one exists. Thanks.