You need to repair the faucet. If you can identify the brand you can see a parts breakdown to better understand what you need to do. However it is not necessary. The rubber parts have worn and need replaced. Sometimes it's just washers and sometimes it's a cartridge.
If you have a Delta be careful when removing the dome cap to access the parts. You can twist and break the 3/8" copper lines. This usually requires replacing the faucet although hj could probably fix it in 20 minutes .