You can get a "USB crash cart" which is built for this exact purpose, but they're quite expensive: https://www.startech.com/en-us/server-management/notecons01

It'd be cheapest to either borrow a monitor from someone, or take the computer to a place that has one you can use. In my part of the world (rural Canada) most public libraries have a lab or makerspace that can be used for such things.