You could use a linked cell that will return true/false. Then use a formula
that refers to that linked cell:
=--A1
(where A1 is that linked cell)
But maybe you could just use that linked cell and do what you want with
true/false.
=countif(a1:a10,true)
could be used to count the number of checkboxes (that are linked to A1:A10) that
are checked.