Any source (e.g. a mic pre-amp) that has a line-level output could be used as an input on the Line-in connection on a Port, for example.

But… you need to be aware that the Sonos system introduces a small delay between input and output, and this may be unacceptable in a “Live” environment. For example all of the people in the same room as the user of the microphone would hear what the quiz master is saying both directly and (delayed) through the Sonos speakers, and this would probably be very irritating.

And possibly for the speaker too, hearing their voice with a slight delay.