Yes, you can take the ferry to reach sharjah from Al Ghubaiba station, the service comes with an affordable fare of AED 15 for Silver Class and AED 25 for Gold Class. However, the journey is free for people of determination and children below five.
Please note that Salik account balance is non-refundable or transferable. You can keep your balance in your Salik account for 5 years. If you do not perform any transaction on the account, such as crossing under one of the gates of Salik or refilling the account during this period, the balance will be confiscated.