Add field to job manager submit job form

add_fieldPjob_submit.php

<?php
/**
 * Add a Field to the Job Submission Form:
 */
add_filter( 'submit_job_form_fields', 'custom_job_submission_fields' );
function custom_job_submission_fields( $fields ) {
    $fields['job']['custom_field'] = array(
        'label'       => __( 'Custom Field', 'text-domain' ),
        'type'        => 'text',
        'required'    => false,
        'placeholder' => __( 'Enter custom value', 'text-domain' ),
        'priority'    => 10,
    );
    return $fields;
}

/**
 * Save the Field Value:
 */
add_action( 'job_manager_update_job_data', 'save_custom_job_field', 10, 2 );
function save_custom_job_field( $job_id, $values ) {
    if ( isset( $values['job']['custom_field'] ) ) {
        update_post_meta( $job_id, '_custom_field', sanitize_text_field( $values['job']['custom_field'] ) );
    }
}

/**
 * Display the Field Value:
 */
add_action( 'single_job_listing_meta_end', 'display_custom_job_field' );
function display_custom_job_field() {
    global $post;
    $custom_field = get_post_meta( $post->ID, '_custom_field', true );
    if ( ! empty( $custom_field ) ) {
        echo '<li>' . esc_html( $custom_field ) . '</li>';
    }
}