testing voltage on a molex connector

I have one of these connectors.

I have an ACDC adaptor plugged into the wall and the cable off it is a molex connector.

I want to test the voltage on the molex connector.

a)does it have to be plugged into a device(so I backprobe)? Or can I just stick probes in the front when it's not connected to a device.

now the following one is the most important question.

b)I can stick the red wire from the multi-meter on the red connector of the molex, the red connector on the molex should be 5V

The black connector on the multi-meter, I suppose i'd put on a metal case.

NOW..

If I put the black probe onto the black of the molex connector, then am I damaging anything? might I break something?

if so, then what ? the multimeter? any damage to the molex connector?