Use the VoiceOver modifier on Mac
You enter VoiceOver commands by pressing the VoiceOver modifier and one or more other keys. For example, to open the VoiceOver Help menu, you press the VoiceOver modifier and the H key. When VoiceOver commands appear as VO-key, VO represents the VoiceOver modifier. For example, VO-Shift-M means to press the VoiceOver modifier along with the Shift and M keys at the same time.
You specify the VoiceOver modifier you want to use in VoiceOver Utility. You can also 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.