To check what are the patches that are installed in your computer, we can use Get-HotFix command.

Open PowerShell console and type Get-HotFix.

You can also do this via WMI commands in PowerShell:
get-wmiobject -class win32_quickfixengineering

To check if a specific patch is installed on a remote computer, an Admin can use the below simple PowerShell command:

Get-HotFix KB2775511 -ComputerName <computername> -Credential domain\Administrator

Now this will prompt to enter your password and then the following results are displayed.