Can I use a mod that says 1.8 for my 1.8.8 minecraft?

No, you have to get the correct version. Wait a bit longer and it may update.

Officially? NO… It's not designed for your desired version of Minecraft, so it may not work or cause additional problems.

Unofficially? NOT RECOMMENDED. How mods are designed, they're specifically written for a certain version of Minecraft & with every update, the files that are modified can be overwritten… Forcing modders to review the updated code on the files to re-modify.

While v1.8.8 is compatible with v1.8 servers & potentially mods (as the updates haven't added new content, mostly bug fixes), it's not recommended since those mod files could be using an older version of said files that the game is expecting. This can cause some undesirable results, like crashing the game & potentially corrupting save data. Therefore, it's a PROCEED AT YOUR OWN RISK deal.

Yes. If it's 1.8 mod, it works with all 1.8 versions.