Most of the time you want to get the IDs of the products in the cart so that you can make some comparison with some other logic - example settings in the backend.
In such a case you can extend the answer from @Rohil_PHPBeginner and return the IDs in an array as follows :
<?php
function njengah_get_ids_of_products_in_cart(){
global $woocommerce;
$productsInCart = array();
$items = $woocommerce->cart->get_cart();
foreach($items as $item => $values) {
$_product = wc_get_product( $values['data']->get_id());
/* Display Cart Items Content */
echo "<b>".$_product->get_title().'</b> <br> Quantity: '.$values['quantity'].'<br>';
$price = get_post_meta($values['product_id'] , '_price', true);
echo " Price: ".$price."<br>";
/**Get IDs and in put them in an Array**/
$productsInCart_Ids[] = $_product->get_id();
}
/** To Display **/
print_r($productsInCart_Ids);
/**To Return for Comparision with some Other Logic**/
return $productsInCart_Ids;
}