Use the VoiceOver modifier on Mac
The VoiceOver modifier is a key or set of keys you press with one or more other keys to enter VoiceOver commands. You can set the VoiceOver modifier to be the Caps Lock key or the Control and Option keys pressed at the same time.
VoiceOver commands are represented as VO-key, where VO represents the VoiceOver modifier. For example, the VoiceOver command VO-Shift-M means you press the VoiceOver modifier along with the Shift and M keys at the same time. Depending on the VoiceOver modifier you’re using, you press Caps Lock-Shift-M or Control-Option-Shift-M.
You can lock the VoiceOver modifier so you don’t have to press it, making it easier to enter VoiceOver commands.
Set the VoiceOver modifier
Open VoiceOver Utility (press VO-F8 when VoiceOver is on).
Click the General category, then from the VoiceOver modifier pop-up menu, select the keys you want to use: the Caps Lock key, the Control and Option keys pressed at the same time, or either of those.
Lock or unlock the VoiceOver modifier
You can make it easier to enter VoiceOver commands by locking the VoiceOver modifier. For example, when the VoiceOver modifier is locked, you enter VO-Shift-M by pressing just the Shift and M keys at the same time.
Lock or unlock the modifier: Press VO-;.
When you use Caps Lock as the VoiceOver modifier, to type uppercase letters, you must quickly press the Caps Lock key twice.