Example Caldera Forms Proccesor See: https://calderaforms.com/doc/getting-submission-data-in-a-form-processor/

config.php

<?php
/**
 * UI for Example Caldera Forms Processor
 *
 * Using the UI generator is way simpler than reverse engineering UI markup and provides for better forward-compatibility
 */
echo Caldera_Forms_Processor_UI::config_fields( my_processor_extra_meta_processor_fields() );

my_processor_extra_meta.php

<?php
/**
 Plugin Name: Caldera Forms Processor To Save Extra Data
 Description: Example Caldera Forms processor to save extra data to post meta
 */

/**
 * Register processor
 */
add_filter( 'caldera_forms_get_form_processors', function( $processors ) {

		$processors['my_processor_extra_meta'] 	= array(
			'name'              =>  'Extra Post Meta',
			'description'       =>  'Save extra data to post meta',
			'processor'	    =>  'my_processor_extra_meta_processor',
			'template' => __DIR__ . '/config.php'
		);
	return $processors;
} );

/**
 * At process, get the post ID and the data and save in post meta
 *
 * @param array $config Processor config
 * @param array $form Form config
 * @param string $process_id Unique process ID for this submission
 *
 * @return void|array
 */
function my_processor_extra_meta_processor( $config, $form, $process_id ){

	$post_id = Caldera_Forms::do_magic_tags( $config[ 'post' ] );
	$field_value = Caldera_Forms::do_magic_tags( $config[ 'field' ] );

	if( is_numeric( $post_id ) && is_object( $post = get_post( $post_id )  ) ){
		update_post_meta( $post_id, 'extra_meta_field', $field_value );
	}



}


/**
 * Setup fields to pass to Caldera_Forms_Processor_UI::config_fields() in config
 *
 * @return array
 */
function my_processor_extra_meta_processor_fields(){
	return array(
		array(
			'id' => 'post',
			'label' => 'Post ID',
			'type' => 'number',
			'required' => true,
			'magic' => true,
			'desc' => 'Post to save field data in. Use {embed_post:ID}'

		),
		array(
			'id'   => 'field',
			'label' => 'Field to save',
			'type' => 'text',
			'required' => true,
			'magic' => true,
		),
	);
}