Show Parent & 1st Level CHILD Category in a Drop Down List Wordpress

Question

I currently have this code that shows all the parent categories in a drop down list.

HTML/PHP Code

<ul>
    <?php 
    $args = array(
    'orderby' => 'name',
    'hierarchical' => 1,
    'taxonomy' => 'category',
    'hide_empty' => 0,
    'parent' => 0,
    );
    $categories = get_categories($args);
    foreach($categories as $category) {
    echo '<li><a href="' . get_category_link($category->cat_ID) . '" title="' . $category->name . '">' . $category->name . '</a></li>';
    } 
    ?>
</ul>

There's no problem with the code below. Actually, it works perfectly! You can see it here at my wordpress website: www.bendaggers.com

What I want to achieve now is how can I add the 1st level child of the parent just what it shown in Image 1 below with the same effect.

Image 1 - Sample

This is what I want to achieve, whenever the user hovers on the listed Parent Category, it will display its 1st level child category as show in the image below.

Image 2 - Sample Parent/Category Hierarchy.

By the way, I need a working code PHP, HTML and CSS also.

I really appreciate you help and efforts, thank you very much!

Some additional Information that might be useful.

• The website is a wordpress website.
• All post are properly categorize (parents, 1st level child category is properly categorized).

Answer 1

You can make function for check If the parent category has child category and pass parent term into newly created function. copy your ablove code and make a function and paste it in your custom function.

And get parent category(you should make first custom function to get paent term) and pass this term to your second custom function