But QEMU/KVM which is the de-facto hypervisor on Linux is harder to detect. Even the others which I mentioned before can be hardened to evade detection.
And if you do a little bit of tinkering and intercept traffic, you can make it so that all the cheating reports from the "AI" never leaves you computer. I've never played with ProctorU but have experimented with a couple of other similar software. They usually send regular reports every five minutes and some anomaly reports (some extra software running on your computer, another person in room, face not visible, etc) when something happens. You need to intercept and modify traffic to not send these anomaly reports. This is easier if its browser based, but you need to install systemwide certs if its install-able software, and a lot more work if they utilize certificate pinning inside binary install-able software. I have never encountered the last one though.