I know well how to create custom form field in joomla module settings as written in the accepted answer of this question which is basically extending JFormField class.
Now what i want to do is suppose there is a custom form field type "unique id" in module's settings page in admin panel, user of the module puts some value in the textbox of this field, and when module settings is saved then that field with value is included in the param field in database table(#_modules) for this module.
But what i want is that i want to save that field value in another table. Look like i need to override some classes when module settngs data is saved, so for this i need quick help or what other ways i can achieve that ? FYI i just don't want to put a form in module at front end to get input for that field from user, i want to do that from module settings page in admin panel which i guess is logical. Thanks in advance for saving my time.