add_filter( 'gform_pre_submission_filter', 'pre_submission_filter' );
function pre_submission_filter( $form ) {

	// foreach( $form['fields'] as $field )  {
	// 	//NOTE: replace 3 with your checkbox field id
	// 	$field_id = 5;
	// 	if ( $field->id != $field_id ) {
	// 		continue;
	// 	}

	// 	print_r($field->defaultValue);

	// }

	print_r( $form['fields'][6]->defaultValue );

}