You cannot. No releases and all the code files are "placeholder.cpp"
Who that is I don't know as it is not displayed anywhere on the website and the the github repo is published by "LazoVelko". Who this is I don't know either. For all I know they are a russian hacker and a future version of this software is going to add an exploit. That is why you should probably think twice about downloading and installing software published by an anonymous person without the source code being available.
I'm not anonymous, this is my name irl.
Neverclick is digitally signed with Microsoft Trusted Signing (now known as Azure Artifact Signing). I had to send them my personal information like my address and ID to get my identity verified so that I'd get approved for it. Additionally, Neverclick doesn't require admin privileges to run, and it works completely offline so you can block it via firewall and it'll work just fine.
Is there anything else I can say or do to put your mind at ease?
And they still have a repository with the code available as well, so it doesn't mislead anyone into believing that they are source available or open source: https://github.com/Keypirinha/Packages