The sky tower and peak galleria are in Victoria Peak Park, you can travel by foot.
You can take bus 15B at Caroline Hill Road, Leighton Road from Causeway to Victoria Peak;Or take MTR at Causeway Bay station to Admiralty Station and then change to bus 15 to the peak.

The bus15B seems stop operating at 19:00. Maybe you can double back by bus15 and MTR; or take the cable down to Central and transfer to MTR to Causeway.