How to use ffmpeg to save video and audio streams to a file in Linux

My computer is Linux OS, and now I have a USB HDMI capture card, the chip is ms2109, it is compatible with UVC, you can think of it as a webcam.

I tried to use obs to do this work, but obs does not seem to be able to capture audio from the capture card (ALSA), only the video can be seen, and I did not find a solution.

I can get the image and sound of the capture card through the following commands of ffplay, and they can work normally.

ffplay -f alsa -i hw:1
ffplay -f video4linux2 -framerate 60 -video_size 1920x1080 -input_format mjpeg /dev/video0

How to save video and audio to file at the same time through ffmpeg?

Can I see the preview of ffmpeg in real time while it is working?