A common problem I found in my laptops was the microphone of headphones not being recognized correctly. In pavucontrol all I can see is the internal microphone:

Pavucontrol withot headphones mic

The solution is to enable a specific flag for your sound card (not always available). In the case of a Mi Notebook Pro 2018 I created this file:

/etc/modprobe.d/alsa-base.conf


options snd-hda-intel model=alc298-dell1

After a reboot everything will be working.

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