Weird. Are you using an unusual keyboard layout? (You can see if you go to > System Preferences... > Keyboard > Input Sources). Mine is just called "U.S.". It could also be some third-party software messing with input, possibly bundled with the keyboard itself.
If the keyboard is, in fact, typing different characters but they look the same in RStudio, you may just need a font which differentiates them. In Fira Code and the Solarized Dark theme, they look and are highlighted differently:
You could also try dragging the glyph in from Font Book to ensure it works with a proper caret (U+005E; confusing called "circumflex accent").