Below screenshot shows the section wherein hooks will be added.

Add the following codes in your theme’s functions.php file.
Section at the top of results page
add_action('wpcargo_before_track_details', 'custom_wpcargo_before_track_details' );
function custom_wpcargo_before_track_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_before_track_details</strong></p>';
}
Section to add in header content
add_action('wpcargo_track_header_details', 'custom_wpcargo_track_header_details' );
function custom_wpcargo_track_header_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_track_header_details</strong></p>';
}
Section after the header details
add_action('wpcargo_track_after_header_details', 'custom_wpcargo_track_after_header_details' );
function custom_wpcargo_track_after_header_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_track_after_header_details</strong></p>';
}
Section to add in shipper/receiver content
add_action('wpcargo_track_shipper_details', 'custom_wpcargo_track_shipper_details' );
function custom_wpcargo_track_shipper_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_track_shipper_details</strong></p>';
}
Section before shipment details
add_action('wpcargo_before_shipment_details', 'custom_wpcargo_before_shipment_details' );
function custom_wpcargo_before_shipment_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_before_shipment_details</strong></p>';
}
Section after shipment details
add_action('wpcargo_track_shipment_details', 'custom_wpcargo_track_shipment_details' );
function custom_wpcargo_track_shipment_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_track_shipment_details</strong></p>';
}
Section after shipment history
add_action('wpcargo_after_track_details', 'custom_wpcargo_after_track_details' );
function custom_wpcargo_after_track_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_after_track_details</strong></p>';
}
Section after package table
add_action('wpcargo_after_package_details', 'custom_wpcargo_after_package_details' );
function custom_wpcargo_after_package_details( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_after_package_details</strong></p>';
}
Section after package totals
add_action('wpcargo_after_package_totals', 'custom_wpcargo_after_package_totals' );
function custom_wpcargo_after_package_totals( $shipment ){
echo '<p style="color: #F44336;"><strong>wpcargo_after_package_totals</strong></p>';
}
How to display my custom dynamic field on the results

The variable $shipment returns value of shipment ID and shipment number. Copy and paste below codes on your child theme functions.php file. Replace the custom_meta_field with the name of your meta key to display its value.
add_action('wpcargo_track_shipment_details', 'custom_wpcargo_track_shipment_details' );
function custom_wpcargo_track_shipment_details( $shipment ){
$shipment_id = $shipment->ID;
$custom_meta_field = get_post_meta( $shipment_id, 'custom_meta_field', true );
echo '<p style="color: #F44336;"><strong>Custom meta field: </strong>'.$custom_meta_field.'</p>';
}