As others have said, you can use the DME information from a TACAN, but not the VOR information.
However (someone please correct me if I'm wrong) there are other beacons known as VORTACs, which are a TACAN co-located with an ordinary VOR. So military aircraft can use them as a TACAN, and civilian aircraft can use them as if they were a co-located VOR/DME.
FFF
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