custom shipping message on checkout screen.

gistfile1.php

<?php

add_action( 'woocommerce_before_checkout_form', 'my_custom_shipping_message' );
 
function my_custom_shipping_message( ) {
  
  global $woocommerce;
    
    foreach ( $woocommerce->cart->get_cart() as $cart_item_key => $values ) {
  			$_product = $values['data'];
    
        /**
        * check if product is in category, if yes, echo out message.
        **/
    }
  
}