Is there an application like OneNote for Mac/iOS?

Microsoft has released a version of OneNote for Mac. It is available in the App Store for users with OS X 10.9 or later.

Outline 2.0, released on the Mac App Store ($40) in December 2013, seeks to mimic OneNote and even sync with OneNote notebooks hosted on SkyDrive. It has a companion iPad app too, sold separately on the App Store. Polarized set of reviews though.

Also, Microsoft Office 2014 for Mac may include OneNote.

Outline (MAS) https://itunes.apple.com/us/app/outline/id604802021?mt=12

The OneNote app (version 16.x) can be downloaded for O365 subscribers

• https://portal.office.com

If for some reason, you need a really old version, you can try installing the unsupported Office 2011 Mac, which has One Note inbuilt. While installing you can choose to install only one note, excluding the rest.