There is the same in the god ol' AtmEga328 (ie all Arduino boards). I fixed a little bit mask in the core libraries and now I can read the corechip temperature as analog 8. It is not very accurate, but has a large range -40 C .. +80 C. Mine returns value 340 for -15C (fresh out of the freezer), 375 for 20C
So, without having a Due at hand, I cant see how to enable it there.