calendar-move-hook

calendar-move-hook is a variable defined in `calendar.el'.
Its value is

nil

• This variable may be risky if used as a file-local variable.

Documentation:
List of functions called whenever the cursor moves in the calendar.
For example,

(add-hook 'calendar-move-hook (lambda () (diary-view-entries 1)))

redisplays the diary for whatever date the cursor is moved to.

You can customize this variable.