If you want to be among the first to install iOS 10 or macOS Sierra, this post is for you. Before we get started, though, you should know that as beta products, they may have bugs. 
So to avoid any errors and to prevent you from "downgrading" the operating system version later, make sure that:
1. Have created at least one backup of your device via iTunes or your computer.
2. Do not use your primary device
3. Expect short battery life and performance
If after all that we mentioned above you still want to upgrade to the beta version, read below, if not, turn the page and... always friends.
For all consumers (upgrade will be available in July)
First, to enter the Apple Beta Software Program you will need to use your Apple ID to sign in.
Next, you'll need to sign up for both iOS and macOS Sierra to get Apple to choose you. Follow the instructions carefully, and you'll end up with a shiny new beta profile for your phone and computer.
Then you'll have to wait, because unfortunately the iOS 10 and macOS Sierra public beta program starts in July.
If you are a developer (update is already available)
It's much easier, but also more expensive, because you'll have to sign up for the Apple Developer Program, which costs $99 per year. It's probably not worth it if you just want the beta.
Simply log in to the Apple Developer Download Center and follow the instructions.
