Easiest way I can think of is that you can use text substitution (System Settings -> Keyboard -> Text Replacements...) to set a string of characters that should

Easiest way I can think of is that you can use text substitution (System Settings -> Keyboard -> Text Replacements...) to set a string of characters that should substitute to the superscript characters (you can look it up with the globe key to set it up initially). So you could make e.g. [1] map to ¹, [2] map to ², etc. You could also use this trick on i(Pad)OS (Settings -> General -> Keyboard -> Text Substitutions). In fact, the substitutions should sync across if you're logged into the same Apple ID.