command-remapping is a built-in function in `C source code'.

(command-remapping COMMAND &optional POSITION KEYMAPS)

Return the remapping for command COMMAND.
Returns nil if COMMAND is not remapped (or not a symbol).

If the optional argument POSITION is non-nil, it specifies a mouse
position as returned by `event-start' and `event-end', and the
remapping occurs in the keymaps associated with it. It can also be a
number or marker, in which case the keymap properties at the specified
buffer position instead of point are used. The KEYMAPS argument is
ignored if POSITION is non-nil.

If the optional argument KEYMAPS is non-nil, it should be a list of
keymaps to search for command remapping. Otherwise, search for the
remapping in all currently active keymaps.