Conditional fields based on user login status?

Hello guys,

I created a quiz field on my CF7 form, it works fine, but I wanna show this field only to guest users / non-logged-in users, and it would be invisible and disabled to logged-in users, how could I do?

I have tried CSS way, it can show / hide fields based on user login status, but cannot disable the field for logged-in users and cause errors when submitting.

Any help would be appreciated.

Qilin