Display field value on the WooCommerce order edition page and emails

functions.php

<?php
//* Do NOT include the opening php tag shown above. Copy the code shown below.

//* Display field value on the order edition page
add_action( 'woocommerce_admin_order_data_after_billing_address', 'wps_select_checkout_field_display_admin_order_meta', 10, 1 );
function wps_select_checkout_field_display_admin_order_meta($order){

	echo '<p><strong>'.__('Delivery option').':</strong> ' . get_post_meta( $order->id, 'daypart', true ) . '</p>';

}

//* Add selection field value to emails
add_filter('woocommerce_email_order_meta_keys', 'wps_select_order_meta_keys');
function wps_select_order_meta_keys( $keys ) {

	$keys['Daypart:'] = 'daypart';
	return $keys;
	
}