ffmpeg -video_size 1920x1080 -framerate 60 / # Resolution + framerate
-f x11grab -i :0.0+0,0 / # screen
-f pulse -i alsa_output.pci-0000_00_1f.3.analog-stereo.monitor test3.mkv # Audio
You can have the audio input with:
pacmd list-sources ffmpeg -video_size 1920x1080 -framerate 60 -f x11grab -i :0.0+0,0 -f pulse -i alsa_output.pci-0000_00_1f.3.analog-stereo.monitor test3.mkv