* first
  :PROPERTIES:
  :CUSTOM_ID: first
  :END:

#+name: heading-id
#+begin_src emacs-lisp :var point=(point)
  (format "%s at %d" (org-entry-get point "CUSTOM_ID") point)
#+end_src

#+RESULTS: heading-id
: first at 53

* second
  :PROPERTIES:
  :CUSTOM_ID: second
  :END:

#+call: heading-id(point=(point))

#+RESULTS: heading-id(point=(point))
: first at 53