Simple mixer control 'Mic',0 Front Left: Playback 0 [0%] [-34.50dB] [on] Front Right: Playback 0 [0%] [-34.50dB] [on]
This plays any noise from the mic input.
Turning it off makes no difference since capture is turned off anyway:
This is a loopback mixer element, it has nothing to do with capture stream.
The likely culprit of the static noises is the signal from the analog loopback. In some cases, you can disable the whole loopback via "Loopback Mixing" mixer element on the fly. In some cases, you'd need to disable each mixer input (e.g. "Mic Playback Switch"). In some cases (e.g. on some Sony and Dell laptops), you'd need to disable the complete analog loopback at the initialization.
The last one can be done via the early patching or sysfs reconfiguration, pass "mixer_nid = 0" hint. See HD-Audio.txt for a brief instruction.
Sadly, that did not help.
Cheers, Julian