How can I encrypt or hash a link?

Need more context. You can do a sha256 hash and then can compare against it but can't "decrypt" back to the original link. If it's possible for someone to intercept the URL and it's super sensitive then you can salt it too (Google that, lots of things here to learn about). If you want to actually encrypt it and decrypt it then you need a secure way of storing the decryption keys or decide when and where and who decrypts it. Lots of stuff to talk about here. Maybe receive your use case more?