All of the Call of Duty games up to and including Call of Duty: Advanced Warfare are available for the Xbox 360. The ones released after that are only on the current consoles.
If you happen to have your original Xbox 360 disc copy of Call of Duty 4: Modern Warfare lying around, you simply need to stick it in your Xbox One and away you go. You can also purchase a digital version of the Xbox 360 game on the Xbox Store.
