To see the notes you write on your Mac on your other devices, just set up Notes to use your Internet accounts. If you have an iCloud account and you upgrade your notes, you can apply paragraph styles, add checklists, attach map locations, lock notes, and even add people to your notes to collaborate with them. For more information, see What is iCloud.
To add accounts to Notes, do the following:
Choose Notes > Accounts.
All of your configured Internet accounts are listed in the sidebar.
Do one of the following:
If the account you want to use with Notes is listed in the sidebar, select the account, then select Notes in the list of features (on the right).
You might need to scroll through the list of features to see Notes. If Notes isn’t listed, the Internet account doesn’t support notes.
If the account you want to use with Notes isn’t listed in the sidebar, click the Add button 
, select the account type on the right, then follow the onscreen instructions. When you set up the account, select Notes in the list of features (on the right).
If you haven’t signed up for an account on the provider’s website, you might need to go to the site to create an account first.
Set up the same Internet accounts on any other Mac computers and iOS devices where you want to see your notes. See the iPhone, iPad, or iPod touch user guide for more details. If your device doesn’t use the latest version of iOS, get the user guide for iPhone, iPad, or iPod touch from the Apple Support manuals website.
Now all notes stored in the accounts you set up are visible on all your devices.
Notes you create in iCloud or another Internet account appear automatically in the Notes app on your iOS devices and Mac computers where you use the same accounts. If you store notes only on your Mac, they don’t appear on your other devices.
If you’re using upgraded iCloud notes, your notes are only visible on devices that use OS X v10.11 or later or iOS 9 or later. You can’t access upgraded notes on devices with earlier versions of OS X or iOS. If you lock a note, it is only visible on devices with iOS 9.3 or later or OS X v10.11.4 or later. (On devices with earlier versions, you won’t see locked notes at all.)
You can view and edit all of your iCloud notes in an Internet browser on iCloud.com.
You can change the way Notes works for you.
Sort notes: Choose Notes > Preferences, click the “Sort notes by” pop-up menu, then choose how you want your notes sorted.
Choose the format for new notes: Choose Notes > Preferences, click the “New notes start with” pop-up menu, then choose the default format for the first line of text.
Choose the default text size: Choose Notes > Preferences, then use the slider to choose the default text size for all text in Notes.
Tip: If you don’t want to change the default text size, but want to view an entire note larger or smaller, choose View > Zoom In or View > Zoom Out.