how to create posts with select dropdown dynamic category

sorry for my english, to expose my problem, I am currently using the plugin Dynamic Select for Contact Form 7, I can thus retrieve through a function the list of my categories in a select.

function cf7_dynamic_select () {

$ output = array ('- - -' => '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 ('listecategories', 'cf7_dynamic_select', 10, 2);

My objective is to create a new article with a category according to the choice of the user’s select option.
but in the “Custom Taxonomy” part of your plugin you do not offer my select fields.

help please ??