It is not a question; I write so that others can do it and share their solutions to the problem. Let's suppose that we have added a field for the genre and another field for the user about. What we want is to show that data in Joomla articles.

$userId = JFactory::getUser($this->item->created_by)->id;
$db = JFactory::getDbo();
$query = $db->getQuery(true);
$query->select('value');
$query->from($db->quoteName('#__fields_values'));
$query->where($db->quoteName('item_id')." = ".$db->quote($userId));

$db->setQuery($query);
$fields = $db->loadColumn();
foreach ($fields as $field) {
    echo $field;
}

This way we are obtaining the data directly and from the user who has created the article.

I want to know how they get the values of custom user fields within Joomla articles. This is to contribute ideas and ways to solve it.