dihydrobenzene doesn't really contain benzene
NOTE: The post previously had 1,3 cyclohexadiene mislabeled as 1,2 cyclohexadiene. Mistake noted by Cesium.
dihydrobenzene comes in two forms. These are also known as:
1) 1,3 cyclohexadiene
and
2) 1,4 cyclohexadiene
(or if you wanted you could do the ortho,para naming)
but the key difference between these compounds and dichlorobenzene is that these, while still a derivative of benzene, do not have 3 alternating double bonds and are not aromatic.
If you are confused of the exact structure I found them at sigmaaldrich.com searching for dihydrobenzene.
The dipole moment of the 1,3 cyclohexadiene form makes sense considering the molecule is no longer symetrical (as in the para-dichlorobenzene or the 1,4 cyclohexadiene). As for the dipole moment of the 1,4 cyclohexadiene I really have no idea, it shouldn't have much, if any dipole moment.