WooCommerce custom checkbox $_POST issue on checkout

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I have found a solution:

// 2. Display T&C @ Single Order Page 

add_action( 'woocommerce_admin_order_data_after_billing_address', 'display_optout_acceptance', 10, 1 );

function display_optout_acceptance( $order ) {
$nosignoptout = get_post_meta( $order->get_id(), 'nosign', true );
if ( $nosignoptout == 1) {
    echo '<p><strong>Shipping Opt-Out: </strong>Selected</p>';
} else echo '<p><strong>Shipping Opt-Out: </strong>Not Selected</p>';
}