You can, yes. You need a SATA cable which likely came with your mainboard and connect it to your PSU as well. I'd still recommend to buy a SSD and copy your OS & files over to that though because HDDs are pretty slow and laptops typically also use low RPM HDDs. Your case also likely won't have any 2.5" brackets to properly mount it so you may have to work out some cheap DIY solution, but if you read my other comment in theory you could have it just dangling too for a while.