A WordPress plugin that adds the PHP version next to the WordPress version in the admin dashboard.

add-php-version-to-admin-footer.php

<?php
/**
 * Plugin Name: Add PHP version to Admin Footer
 * Plugin URI: https://gist.github.com/mistercorey/229e972f44855e9ee741f28d7c37a772
 * Description: Adds the PHP version next to the WordPress version in the administrative dashboard footer
 * Version: 1.0.1
 * Author: Corey Salzano
 * Author URI: https://profiles.wordpress.org/salzano
 * License: GPLv2 or later
 * License URI: http://www.gnu.org/licenses/gpl-2.0.html
 */

class Add_PHP_Version_To_Admin_Footer{
	function hooks() {
		add_filter( 'update_footer', array( $this, 'add_php_version' ), 11 );
	}

	function add_php_version( $text ) {
	    return sprintf( '%s, PHP version %s', $text, phpversion() );
	}
}
$salzano_version_adder = new Add_PHP_Version_To_Admin_Footer();
$salzano_version_adder->hooks();