An online meeting or a lecture video plays through your computer, not into your microphone. System audio recording captures that sound directly.
Choosing the source
Start a voice recording in the desktop editor and open the recording source picker. Three options: microphone only, system audio only, or microphone plus system audio. The third one is the meeting setting, your voice and everyone else in one track. There is also an input device picker if you use an external microphone.
Permissions
Recording system audio needs the screen capture permission on macOS, and Grape shows a button that opens the right pane in System Settings the first time. Microphone recording asks for microphone permission separately. On platforms where system audio capture is not supported, Grape says so rather than recording silence.
Mobile records the microphone
Phones do not expose other apps' audio, so mobile recording is microphone only. For a call on your computer, record on desktop and let sync carry the note everywhere.
The usual workflow
Record the meeting with microphone plus system audio, take short notes while it runs, then transcribe and let a quick prompt summarize the transcript under your own notes.