Onclick for custom module doctype in core module form - how to trigger?

Onclick function for field inside a table of custom module doctype is not triggered inside “Customer” doctype of core erp module. Not able to trigger using jquery either. Please help.

  1. Share your use case
  2. Share the code you have tried, so someone can try to help

This is the code that I have used:

frappe.ui.form.on("Customer", {
   //custom_field belongs to custom_doctype created inside 'custom_module'
   //custom_field is a column inside a table(custom_doctype) in this form
	  custom_field: function() {