How to load category image in frontend?

We have created a megamenu and want to load the category image on the menu. I’m not sure how to load that.

As of now, we have just hardcoded the image.

Below is the code:

< ?php
namespace ButterflyMegamenuBlock;
class Categorylist extends MagentoFrameworkViewElementTemplate
{    
    protected $_categoryHelper;
    protected $categoryFactory;
    protected $_catalogLayer;
    protected $_categoryRepository;


    public function __construct(
        MagentoCatalogBlockProductContext $context,     
        MagentoCatalogHelperCategory $categoryHelper,        
    MagentoCatalogModelCategoryRepository $categoryRepository,        

        array $data = []
    ) {


        $this->_categoryHelper = $categoryHelper;   
    $this->_categoryRepository = $categoryRepository;
        parent::__construct(
            $context,          
            $data
        );


    }

    public function getStoreCategories($sorted = false, $asCollection = false, $toLoad = true)
    {
        return $this->_categoryHelper->getStoreCategories($sorted , $asCollection, $toLoad);
    }

    public function getCategoryById($categoryId) 
    {
        return $this->_categoryRepository->get($categoryId);

    }

public function  getSubcategories($categories, $parent= '') {
    $i = 0;
    $array= '
';
    foreach($categories->getChildrenCategories() as $category) {
        $array .= '
';
        $cat_image = 'https://techcrunch.com/wp-content/uploads/2010/10/pirate.jpg?w=990&crop=1';
        if($i == 3 && $parent == '' && $cat_image != ""){
            $array .= '';
            $array .= '
';
        }
        $array .= '' .
                  $category->getName() . "n";
        if($category->hasChildren()) {
            $children = $this->getCategoryById($category->getId());
             $array .=  $this->getSubcategories($children, 'child');
            }
         $array .= '
';
         $i++;
    }
    return  $array . '
';
}


}

Any help will be appreciated!