apt-cdrom is a simple command to add CDROMs to apt’s sources.list file. Its syntax is a variation on this basic command line
# apt-cdrom add
apt-cdrom uses information from your /etc/fstab if you don’t specify where’s the CDROM drive.
Example :-
#apt-cdrom -d=/mnt/cdrom add
If you want more information and available option check apt-cdrom man page