This article explains how to install Windows 10 on an old MacBook running El Capitan. Apple made sure to make our lives difficult but installation is still doable.
Download the Windows 10 .iso file from your preferred location (MSDN, torrentz etc) and place the .iso file on the desktop.
Insert a USB drive in one of the Mac’s ports. This USB drive will be formatted so make sure that all its contents are backed up.
Launch the Disk Utility, select the USB drive from the list, then press Erase on the top of the window and make sure MS-DOS (FAT) format is selected. Then click Erase button to start the process.
Once formatting is complete, launch Boot Camp assistant and click Continue. Make sure all three options are selected as per below screenshot.
If the first option “Create a Windows 7 or later version install disk” is missing, please follow the article of the link to make it appears before continuing the process on this article.
Then click Continue again. If the .iso file is placed on the Desktop and the USB drive is FAT formatted, Boot Camp Assistant will automatically detect them as per screenshot below.
Click Continue again to manage the size of the Windows partition and then the installation process will initiate!
Once Windows 10 are installed, you will notice some key mac features like right click of the Track Pad are not working.
In order to install Boot Camp drivers, please follow the article “Boot Camp x64 is unsupported on this computer model“.