Hi,
It would have been great if you could have provided a screenshot of the settings of the custom field.
Supposing that your custom field is of one of the type "single dropdown", "multiple dropdown", "radio" or "checkbox", to get the titles of the values on the product details page, and supposing that the product doesn't have variants, you can use such code:
<?php
$fieldClass = hikashop_get('class.field');
$field = $fieldClass->getField('xxx', 'product');
echo $fieldClass->show($field,$this->element->xxx);
?>
where xxx is the column name of the custom field.
So, if I understand correctly, you have a URL for the value, and the label of the link as title.
In that case, the code will probably look like this:
<?php
$fieldClass = hikashop_get('class.field');
$field = $fieldClass->getField('xxx', 'product');
?>
<a href="<?php echo $this->element->xxx; ?>"><?php echo $fieldClass->show($field,$this->element->xxx); ?></a>