**Edit:**

This is a not good answer, you can follow the @adjco answer. Try to use Service Contract.

Try to inject `Magento\Sales\Api\Data\TransactionSearchResultInterfaceFactory` into your constructor:

    protected $transactions;
    
    public function __constructor(
      \Magento\Sales\Api\Data\TransactionSearchResultInterfaceFactory $transactions,
      ......
    )
    {
      $this->transactions = $transactions;
    }

In your method:

    $transactions = $this->transactions->create()->addOrderIdFilter($orderId);
    $transactions->getItems();

If `Magento\Sales\Api\Data\TransactionSearchResultInterfaceFactory` doesn't work, try to use `\Magento\Sales\Model\ResourceModel\Order\Payment\Transaction\CollectionFactory`. I'm not test yet both of them.