Normally, when writing a cheque, you need to write payee name on the cheque. If you don't know who to make a cheque payable to, how to write a cash cheque?
To write a Cash cheque, you just need to write "Cash" on the payee line instead of writing the payee name. But you should avoid to use Cash cheque as it is risky. Cash cheque just like Cash, anyone who has the cheque can cash or deposit the cheque. If the cash cheque is lost or stolen, anyone who has the cheque can cach it unless you inform the bank to stop the cheque payment first.
On the other hand, if you receive a cash cheque, you should go to the bank and deposit it imeediately. Otherwise it has a chance to be stolen.