I Can't make a microphone work on a Mac Mini

Hi everyone,
First of all happy new year .
I got a present consisting of headphones with a microphone and although the headphone work very well, the built-in micro doesn't, I checked the sound settings but I couldn't solve the problem.
Would anybody have an idea? I have the latest version of macos and the computer is from the last year.
Thanks in advance and best regards.
Rafa.