i am using the front jack (front mic). so what worked for me might also work for you:
fire up alsamixer from the terminal by typing
next fire up another terminal and the arecord loopback so you can hear actually what your motherfucking mic is receiving:
arecord | aplay
here are my playback settings (click to enlarge the pic :) ):
so what you wanna do is: make sure front, fornt mic, mic is 100%.
then go to capture screen by pressing F4:
here select your mic: i selected front mic and mic. also max the capture and capture1.
here is the cunt part! i had no idea about the digital setting! apparently you need to set it up in such a level that you can actually make the mic work. when i set it to 100% my mic was giving out a very distorted sound. so i leveled it to around 54. play with it until you hear a clear sound.
hope this helped.