Mic not working but blue indicator show nearly 0
You need to provide some information for us to help you.
Is the headphone/mic bluetooth or wired (USB)?
What soundcard do you have?
In terminal open
Hit F5 to display all channels and post a screenshot.
Unmute any by selecting then hit M, also increase level.
Also can check Auto-mute is not Enabled.
I have recorded a video but no sound. but I hear hisss sound. I think mic not working. but work on windows.
You have Spreaker and Mic muted. Have you tried unmuting them?
where should i change?
To unmute a sound channel in
alsamixer, just pan across to the channel showing as [M] then hit M key to unmute. Also increase the sound level.
Can you answer those initial questions.
Also Hit [F5] in alsamixer shows All the sound channels. If you post a screenshot of All the sound channels then we may find another Mic channel maybe.
I assume you have already had a play with different Auto-Mute Mode and Loopback Mixing enabled/disabled settings.
By wired, I assume 3.5mm jack. If USB, then you could try another USB port.
I am out of ideas.
You can widen your websearch to "alc3236 no mic ubuntu 20.04". Here is one that appears from that search:
how to find audio codec in terminal?
Have you tried different interfaces, I mean trying to play music through the web browser, with media players like VLC, opening an audio file with Audacity, etc?