How can I create Checkbox, within the WooCommerce Product Dashboard, which will Output code only when selected?

I am currently working on a WordPress eCommerce website, where the preferred shopping platform is WooCommerce.

Is there a way to create a Checkbox within the WooCommerce Product Dashboard, which Outputs a piece of coding from within the functions.php file, when the Checkbox is selected?

The coding, within the functions.php would create a Text Box on the Product Page.

The Coding I have so far ...

To create the Checkbox, within the WooCommerce Product Dashboard, I have entered the following code into the functions.php file:

<?php
// Display Fields
add_action('woocommerce_product_options_general_product_data', 'woocommerce_product_custom_fields');

// Save Fields
add_action('woocommerce_process_product_meta', 'woocommerce_product_custom_fields_save');


function woocommerce_product_custom_fields(){
    global $woocommerce, $post;
    echo '<div class="product_custom_field">';
    // Custom Product Checkbox Field
    woocommerce_wp_checkbox(
        array(
            'id'          => '_custom_product_checkbox_field',
            'placeholder' => 'Custom Product Checkbox Field',
            'label'       => __('Custom Product Checkbox Field', 'woocommerce'),
            'desc_tip'    => 'true'
        )
    );
echo '</div>';

}

// Saving Values
function woocommerce_product_custom_fields_save($post_id){
    // Custom Product Text Field
    $woocommerce_custom_product_checkbox_field = $_POST['_custom_product_checkbox_field'];
    if (!empty($woocommerce_custom_product_checkbox_field ))
        update_post_meta($post_id, '_custom_product_checkbox_field', esc_attr($woocommerce_custom_product_checkbox_field ));
}
?>

The coding I have placed, in the functions.php file, as to Output the relevant Custom Text Box, is as follows:

<?php
function add_engrave_text_field() {
    if (is_single('product-url-a')) {
    echo 'Enter your chosen letters:  <span id="character_count"></span>
        <div><table class="variations" cellspacing="0">
            <tbody>
                <tr>
                    <td class="value"><label class="product-custom-text-label" for="custom_text">Custom Text</label></td>
                    <td class="value">
                        <label><input type="text" class="product-counter" name="engrave_text" placeholder="Enter Your Custom Letters ..." maxlength="3" /></label>                        
                    </td>
                </tr>                             
            </tbody>
        </table></div>';
}
}
add_action( 'woocommerce_before_add_to_cart_button', 'add_engrave_text_field', 0 ); 
?>

What would be my next step, so that the Custom Text Box coding will only be Outputted when the Checkbox is selected?

I realise that I could put the code for the Custom Text Box into the content-single-product, however I would ideally not want to do this as it is part of a large group of coding which works out the pricing of the Custom Lettering etc.

Additional Question:

The website is made up of 5 Product Categories. Only Products in one of these Categories allow for Custom Lettering. At present, I am having to manually apply the above coding to each individual product, as I am having to insert the individual slugs into if (is_single('product-slug-a')) Is there a way I could change 'product-slug-a' so that I only have to enter the code once into the functions.php file and it is called for every Product within just one of the Product Categories?