You can travel from Penang to Pangkor Island by car or bus. Then you need to take the ferry for the final leg of the journey.
As for why you’d like to travel to Pangkor, please see: Visiting Pangkor Island – 10 best things to do
Penang to Pangkor Island by car or bus is about 200KM. Buses run from Penang to Lumut (generally). This is a coastal ferry port for Pangkor Island. The trip should take about three and a half to four hours by bus. Currently the ticket price on Arwana Express is RM17.80 one way. They depart from the bus terminal at Butterworth – which is near the ferry terminal and railway station.