Record audio with FFMPEG

ALSA

choose a card number as microphone source

arecord -l

proceed as WAV for starters (MONO: one channel)

ffmpeg -f alsa -i hw:2 -ac 1 output.wav

make sure the microphone is enabled

pavucontrol --> input devices
100%

choose a card number as microphone source

pactl list short sources

enable the microphone as default source

pactl set-default-source echocancel

ready to go

ffmpeg -f pulse -i default -ac 1 output.m4a