I just plug the headphones, but the microphone from headphone is not detected as input device in All settings -> sound

is there any way to change my sound input device from web cam to headphone?

Since you tell us nothing about the headphones (brand/model), how they connect, or what you're plugging them in to (and not even the version of Linux Mint), what do you think we'll be able to say???

If these are wired headphones, and you're plugging them in to a laptop, then chances are that there isn't any support on the headphone jack for an external mic, no matter WHAT OS you're using. You need a cheap $5 Y adapter (Amazon.com has loads), that takes the headphone/microphone single jack, and turns it into a stereo headphone/mono mic. From there, plug it into your headphone jack and mic jack respectively.

it is a logitec, got them at walmart, and they have both plug (headphone, mic) I got them plugged in the only two jacks available in the computer for them audio out (green) audio in (pink)
hope description helps

How, exactly, would it help?? You STILL say nothing about the model, what you're plugging them in to, etc. You only say "Logitech from Walmart" and you're plugging them into your computer, but don't say anything about it, either, and STILL don't say what version of Mint.

Having to guess and ask over and over for details isn't pleasant...read the "Question Guidelines" link in my posting signature. And the better question here is, why would you think it would show up as a different input source?? If you're using the EXISTING input jack, that's exactly where the input will come from.

Have you checked your Pulseaudio Mixer settings to verify that the mike input is not muted by default? It often is.

Also, have you tested the mike with another device to verify that it is mechanically sound?