If you get a video or even better a demo of it happening, he will get banned for sure.
If you don't know how to record a demo:
To start recording the demo: Open console and type record micspammer to start the demo.
To stop recording the demo: Open console and type stop to stop the demo.
If you don't know how to open console:
You have to go to the Game settings and check the enable developer console . After this you can use ` or the assigned key to open and close it.
After stopping the demo, go to the directory you installed CS:GO to (usually SteamLibrary\SteamApps\common\Counter-Strike Global Offensive\csgo) and there should be a micspammer.dem file. Upload this to the forums and admins will be able to play the demo back and see everything going on.

> Trust your technolust