do i need honk kong visa if I'm only on transit

I am traveling Dubai to Shenzhen for business and plan to take cathay pacific airlines to HKG and take the ferry direct from HKG airport o Shenzhen. I am basically only in transit and don't go through HK cutoms.
do I need HK entry permit or no need as I don't pass customs? I have mainland PRC entry permit. I am sri lanka passport holder.