Notes are shared and synced by imap mail servers. Any servers, not only icloud. You can create any mail account, say Yahoo. Add that account on your devices and turned notes on. Next time you go to notes app, when you click notes - you will see accounts. If you choose you can click yahoo and anyone who has that account setup will share notes with you. If you choose icloud or on my iphone/ipad you will either have those synced to your icloud account(synced over your own devices only) or just saved to that phone, without replication.
Usually people come back here and say it is too complicated, but so is the nature of anything with knowing how to use your phone/computer. You learn how or you lose your info, with every transfer from one device to another and iphone life span is not as long as computer's. Good luck.