If you can get a mic into it, then you can get OBS into it...though it's a bit hacky on OBS's side.
More generally, if you can get a mic into it, then you can get *any* app into it, by installing a loopback driver. This one seems to be popular:
VB-Audio Virtual Cable and App's
vb-audio.com
A loopback driver gives you a virtual speaker and a virtual mic, that appear in the same list and behave the same way as the physical mic(s) and speaker(s) that you may have. The virtual speaker doesn't connect to anything except the virtual mic, and vice-versa.
So you connect the app that wants a mic, to that virtual mic, and connect the app you want to feed into it, to that virtual speaker. And there's your connection!
---
Now, if you're doing audio only, OBS is ABSOLUTELY NOT the program you want to use! OBS is terrible with audio. I often recommend that people bypass it altogether and do all of their audio work in either a physical console or a Digital Audio Workstation (DAW), then bring the final soundtrack into OBS as its only audio source to pass through unchanged.
A DAW is essentially a complete sound studio all in one app. It's designed to do exactly that and only that, and it's GOOD at it! Lots of those to choose from, some paid, some free, some work well, others not so much, and there doesn't seem to be much correlation between function and price anymore.