Just some perspective from someone else with a headset and a MacBook Pro as well as a ThinkPad running Linux.
I didn't see this mentioned specifically but are you dual booting Linux and MacOS on your MacBook Pro?
The "FaceTime HD Camera" is the built in camera for the laptop. They also have built in mics.
I have two different headsets. One has a USB plug, the other has a combination jack like yours. On both of them I am able to switch to their input, both with MacOS and Solus. On MacOS, sometimes it automatically switches input and output. Other times it doesn't and I have to manually switch them over.
Just so we're on the same page here's how I change input / output:
- Click the speaker icon, click on the correct output
- Click the speaker icon, click Sound Preferences, go to "Input" and select the correct input. If your headset mic doesn't show up here, it's because MacOS doesn't detect the hardware.
Solus always automatically switches to the right input & output, but I can:
- Click on the speaker icon (plasma)
- Click the settings icon at the lower right
- Click the "Audio" icon on the left and make sure the right devices are active. You should see your headset mic in there, if not the hardware isn't being detected.
A few years ago I dual booted Ubuntu with MacOS on a 2010 MacBook Pro. Through research I had discovered Apple does all sorts of proprietary nonsense in their hardware and drivers. Things that "just work" on non-Apple devices can be flaky on Apple hardware with anything other than MacOS. Brent mentioned this issue in his post as well, I'd recommend checking that link to see if your headset is listed as supported.
Best of luck.