ZoomIt is a screen zoom and annotation tool for presentations that include application demonstrations. ZoomIt runs unobtrusively in the tray and activates with customizable hotkeys to zoom in on an area of the screen, move around while zoomed, and draw on the zoomed image.

ZoomIt works on all versions of Windows and you can use pen input for ZoomIt drawing on tablet PCs. It is available as a free download from Microsoft's Sysinternals, and you can just download it and use it without needing administrator rights on your computer.

Jump to 1:50 to see the cool annotation examples.

The closest macOS solution we could find is DemoPro; which is available in the App Store for a fee.