inicius

If someone else needs some help, here’s the code that worked for me:

function cf7_dynamic_select() {

    $output = array('Área de atuação/Segmento' => '0');
    $args = array(
      'order'=> 'ASC',
      'orderby'=> 'name',
      'hide_empty' => 0 );
    $categories = get_categories($args);
    foreach( $categories as $category ) {
        $output[$category->name] = $category->name;
    }
    return $output;
}
add_filter('my-filter', 'cf7_dynamic_select', 10, 2);

Thanks, John Huebner, for the excelent plugin!