Update 2014-10-02
UCanAccess v2.0.9.1 has added support for calculated fields. We can now read their values directly, and calculated fields are updated in the database as part of INSERT and UPDATE operations.
Previous answer:
As you are probably aware, UCanAccess uses Jackcess to read/write the Access database so it is really a question of whether Jackcess can read a Calculated field. Unfortunately, it cannot (or at least it couldn't do so the last time I checked, which was sometime in the last few months).
On Windows you would have the option of using the JDBC-ODBC Bridge (with all its warts) under Java 7. However, I'm not aware of any other options for Java under Linux.
You may want to visit the Jackcess site on SourceForge and ask about this issue in the discussion forums, or possibly submit a feature request.