A knowledge base article about Zoom: Using annotation tools on a shared screen or whiteboard provided by the UC Berkeley IT Service Hub - Knowledge Portal
Zoom Meeting participants can annotate on a shared screen as a viewer or the one that started sharing your screen.
Some find laptop touchpads and mice awkward to add text and write equations on the whiteboard. Others have used iPads with an Apple Pencil, a Microsoft Surface with a stylus to assist, or a second screen, one for whiteboard and the other for presentations for the meeting itself. Another campus member is using a Huion H420.
You can also use annotation tools when sharing or viewing a whiteboard.