You can verify the card details and see the results of the CVC and postcode checks by saving the customer's card in Stripe.
To prevent card testing, Stripe is sometimes required to not complete CVC and postcode checks on card validations, so they may appear as "unavailable". Those checks will be available on the charge object once an actual payment has been made. Stripe uses machine learning to predict when card testing is likely. These checks may also be unavailable as a cost optimisation if Stripe's machine learning predicts that the card is valid and that performing these checks will not increase the probability of a successful payment.
The card information is verified when the card is saved, but it only verifies that the information is valid. It cannot check credit limits or account balances to guarantee that a card will have sufficient funds when you do decide to charge it.
The card can still be declined or fail for other reasons.