wp jquery datepicker

add css js

/**
 * Load jQuery datepicker.
 *
 * By using the correct hook you don't need to check `is_admin()` first.
 * If jQuery hasn't already been loaded it will be when we request the
 * datepicker script.
 */
function wpse_enqueue_datepicker() {
    // Load the datepicker script (pre-registered in WordPress).
    wp_enqueue_script( 'jquery-ui-datepicker' );

    // You need styling for the datepicker. For simplicity I've linked to Google's hosted jQuery UI CSS.
    wp_register_style( 'jquery-ui', 'http://code.jquery.com/ui/1.11.2/themes/smoothness/jquery-ui.css' );
    wp_enqueue_style( 'jquery-ui' );  
}
add_action( 'wp_enqueue_scripts', 'wpse_enqueue_datepicker' );

using

<script>
    jQuery(document).ready(function($) {
        $("#datepicker").datepicker();
    });
</script>

source _https://stackoverflow.com/questions/27462984/use-jquery-datepicker-in-wordpress