add a control to an existing widget in functions.php

I want to add a custom control to an existing Elementor widget ,a simple "select" drop down to the "title (heading)-widget",that will inject an attribute to the widget heading, based on the selected value from the drop-down list. so this is the code for the control

   add_action('elementor/element/before_section_end', function( $section, $section_id, $args ) {
if( $section->get_name() == 'heading' && $section_id == 'section_title' ){
        'my_custom_control' ,
            'label'        => 'add ID to each heading',
            'type'         => Elementor\Controls_Manager::SELECT,
            'default'      => 'h1',
            'options'      => array( 'h1' => 'h1 ID','h2' => 'h2 ID', 'h3' => 'h3 ID', 'h4' => 'h4 ID'),
            'prefix_class' => 'my-ID-to-each-heading-',
            'label_block'  => true,
     }, 10, 3 );

next I want to catch the value that was selected from this dropdown . (the selection happens of course in the admin dashboard).... can I do it in functions.php ?or do I have to create a new widget for this ?