Determine category in taxonomy of current custom post type

get_the_category is the most obvious answer. Per the Codex:

Returns an array of objects, one object for each category assigned to
the post. This tag may be used outside The Loop by passing a post id
as the parameter.

Or wp_get_post_categories as in this example from the Codex:

$post_categories = wp_get_post_categories( $post_id );
$cats = array();

foreach($post_categories as $c){
    $cat = get_category( $c );
    $cats[] = array( 'name' => $cat->name, 'slug' => $cat->slug );
}

But your question is very light on detail. It is hard to tell exactly what you need.