Supposedly, It should be possible to convert older Access databases (.mdb) to the legacy Pocket Access format (.cdb) through ActiveSync utility by Microsoft. Whenever this is actually possible could not be verified, but considering .cdb files were used on Windows CE platform that is largely discontinued the purpose of this conversion would be something highly specific.
Convert Microsoft Access database to Pocket Access database.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert mdb to cdb on Windows
A synchronization utility for Windows Mobile
Convert from mdb file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.