Magento 2.1: Invoke urlBuilder->getUrl() in a controller in a custom module

actually from controller you can use

$this->_url->getUrl('yourmoduleurl/index/index')

If your controller extend Magento\Framework\App\Action\Action you should follow rules of creation of the controller. So you should implement dependency injection of the parent class constructor (Magento\Framework\App\Action\Action):

/**
 * @param Context $context
 */
public function __construct(Context $context)
{
    parent::__construct($context);
    $this->_objectManager = $context->getObjectManager();
    $this->_eventManager = $context->getEventManager();
    $this->_url = $context->getUrl();
    $this->_actionFlag = $context->getActionFlag();
    $this->_redirect = $context->getRedirect();
    $this->_view = $context->getView();
    $this->messageManager = $context->getMessageManager();
}

Your construct method should look like this after a modifications:

/**
 * @param Context $context
 * @param UrlInterface $urlBuilder
 */
public function __construct(
    Context $context,
    UrlInterface $urlBuilder
) {
    parent::__construct($context);
    $this->urlBuilder = $urlBuilder;
}

NOTE: do not forget to remove old var/generation directory after implementing of modifications, because there are stored the generated files of controllers.