Microsoft has released the ISO files for Windows 10 Insider preview build 10565

Follow these steps to download Insider Preview:

Sign up for the Windows Insider Program, if you haven't already.
Read the system requirements.
Click one of the Download links on this page to download a special file—it's called an ISO file—that you can use to install the preview.
When the download is complete, transfer the ISO file to installation media such as a USB flash drive or DVD.
Boot your PC from the installation media, and then follow the steps to perform a clean install.


Windows Insider Preview Activation

You will need to install the Windows 10 Insider Preview build on a device that has been previously activated with Windows 10 or with a Windows 10 product key. For more details please see the article: Activation in Windows 10.

  Windows 10 Insider Preview Build 10565 ISOs released