Can you help me to change window's appearance in Ubuntu 16.04 to be like this image?
In past, many of the Ubuntu themes had those Mac-Like looks. It's hard to say the exact theme just by looking at the image. However, I have one theme that has same visual looks. The name of the theme is
mac-ithemes-v3 and is provided by old noobslab themes PPA. The problem is this theme is for Ubuntu 14.04 and hasn't been updated for later releases.
However, if you must own this theme, you can grab the deb package for Trusty and install it using
wget -c https://launchpad.net/~noobslab/+archive/ubuntu/themes/+files/mac-ithemes-v3_3.12-c~trusty~NoobsLab.com_all.deb sudo dpkg -i mac-ithemes-v3_3.12-c~trusty~NoobsLab.com_all.deb
You should now be able to use this theme (with some problem) in Xenial Xerus. This package has multiple themes included. You'd select
Mbuntu-mb for that look.
Here is a screenshot of same CCSM program using the theme.