As I understand the question, the scenario would go something like this:
You leave a CD containing information
(for the sake of argument, we'll say
it's a backup of some financial
information from your computer)
sitting on your desk. At some point,
someone enters your office, spots the
CD, pops it into their laptop (which
they just happen to be carrying under
their arm), and copies everything on
it to their hard drive. They then
replace the CD. Later when you return,
it doesn't appear to be exactly
where you left it so you wonder, did
someone copy all of my information and
should I be cancelling my credit cards
now?
If it's a CD (or DVD), then the short answer is no, you have no way of knowing whether the data was copied other than gaining access to the aforementioned laptop and searching for your data.
Now, if it's a USB device, the answer is a definite maybe. Some file systems store the date/time that a file was last accessed and you may be able to see it and tell that way (but I wouldn't count on it).