In previous generations, if you wanted to emulate one game console on another, you'd generally have to use some sort of jailbreak or hack to install unauthorized homebrew apps on the system. Today, thanks in part to Microsoft's Universal Windows Platform, you can download a Nintendo 64 emulator to your Xbox One directly from Microsoft's official store.
The "w64" emulator can download ROMs from a user's linked Microsoft OneDrive account, making it quite simple to import and play homebrew titles or copyrighted games (which we're sure you've personally ripped from your personal collections for completely legal backup purposes). The emulation quality is far from perfect, though. Simple games like Super Mario 64 run pretty well, but other games we tested suffered from very noticeable sound and graphics problems and struggled to run at a full frame rate.