Getting product Image in PHTML in Magento2

   
    (1)  You have to load product to get thumbnail and url .

    <?php $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
    $product = $objectManager->create('Magento\Catalog\Model\Product')->load($_item->getProduct()->getId());
    echo $product->getThumbnail();
    echo  $product->getProductUrl(); ?>


     (2) Get image url

    $imagewidth=200;
    $imageheight=200;
    $imageHelper  = $objectManager->get('\Magento\Catalog\Helper\Image');
    $image_url = $imageHelper->init($product, 'product_page_image_small')->setImageFile($product->getFile())->resize($imagewidth, $imageheight)->getUrl();
    echo $image_url