You will need to report this accident to your insurance company and they will investigate your claim of what happened and the damage sustained to determine if it will covered by your collision or "other than collision", comprehensive, coverage.

It will likely matter what object it was that fell from the pickup and if your car and/or the truck was moving at the time accident. If it is determined that the damage is not covered by collision then it would probably be covered by your comprehensive coverage. With either type of coverage you will have to pay the deductible as part of the claim process.