How to Convert an Object into Array in magento 2

Why not?

$cms = $this->collectionFactory->create()->toOptionArray();
            $options = [
                // your code
                [
                    'label' => __('CMS pages'),
                    'value' => $cms
                ]
            ];

Try Foreach loop will help.

Syntex :

$data = $cms->toArray();

foreach ($variable as $key => $value) 
{

}

let me know if anything you need.

Thanks