Pretty sure they can’t but your disengaged employees can. The problem is that they are afraid to tell you the truth.
If you really want to know what’s on their minds, I’d be happy to chat with them. An outsider who promises to not out them to you is usually able to inspire some candid feedback. Get on my calendar to schedule a time to chat.
Of course, you could also make some assumptions about what they might say. If that’s your preferred next step, check out this fine list created by Michael Stallard.