WordPress Post :

How to Call Custom Menu in WordPress Put Below Code in function.php File

if ( function_exists( 'register_nav_menus' ) ) {
        register_nav_menus(
               array(
                 'main_menu' => __( 'Main Menu', 'cake' ),
                 'secondary_menu' => __( 'Secondary Menu', 'cake' ),
               )
        );
}

After this save your Function.php file and Put Below code in Header.php file

         'main_menu',
          'menu'            => '', 
          'container'       => false, 
          'echo'            => true,
          'fallback_cb'     => false,
          'items_wrap'      => '

%3$s

‘, ‘depth’ => 0 ); wp_nav_menu( $defaults ); ?>

This Code Display Your Menu in Site.