Magento 2 - Get Parent Product IDs

app\code\Fiko\Catalog\Block\SingleProduct.php

<?php

namespace Fiko\Catalog\Block;

use Fiko\Catalog\Helper\Data;

class SingleProduct
{
    public function __construct(Data $helper)
    {
        $this->helper = $helper;
    }

    // How to use it
    public function exampleOfHowToUse()
    {
        $productId = 1;
        return $this->helper->getParentIds($productId);
    }
}

app\code\Fiko\Catalog\Helper\Data.php

<?php

namespace Fiko\Catalog\Helper;

use Magento\Catalog\Model\Product\Type as ProductType;
use Magento\Framework\DataObject;

class Data
{
    /**
     * Constructor
     *
     * @param ProductType $productType
     */
    public function __construct(ProductType $productType)
    {
        $this->productType = $productType;
    }

    /**
     * Retrieve parent products of a product
     *
     * @param int $productId
     * @return array
     */
    public function getParentIds($productId)
    {
        $parentIds = [];
        $productTypes = [];
        $productEmulator = new DataObject();

        foreach (array_keys($this->productType->getTypes()) as $typeId) {
            $productEmulator->setTypeId($typeId);
            $productTypes[$typeId] = $this->productType->factory($productEmulator);
        }
        foreach ($productTypes as $typeInstance) {
            $parentIds[] = $typeInstance->getParentIdsByChild($productId);
        }

        $parentIds = array_merge([], ...$parentIds);
        return $parentIds;
    }
}