Free access to CBL workstations is a must if CBL is to fulfil the expectations of its sponsors. This should extend to 24hr access wherever possible. Simple cabling alarm systems are now available that allow computers and their peripherals to be secured against casual theft, which is the greatest danger. Your computer centre will have details.
Headphones are less easy to secure, which is why personal headphones are recommended.
Don't underestimate the risk of theft or the ingenuity of thieves. Check out your university's insurance cover. It is highly unlikely to provide for the cost-free replacement of stolen or damaged computers.