DMA (Direct Memory Access) is the keyword.

They use this type of hardware:

https://www.raptor-dma.com/raptordma-home/

It's been used to cheat in professional CS:GO tournament from what I remember. They can have a second PC where the cheat run which read the memory of the game on the clean computer and can for example display the position of the other players on a second screen.

Not related to this game, but this has been a thing in the counter strike community for a few years already. This is an example cheat: https://github.com/EngineOwningSoftware/pcileech-webradar And this is the base repo it was forked from that goes into way more technical details: https://github.com/ufrisk/pcileech