Toolhelp32readprocessmemory

[DllImport("Kernel32.dll", SetLastError = true)][return: MarshalAs(UnmanagedType.Bool)]
public static extern bool Toolhelp32ReadProcessMemory(uint th32ProcessID,
   IntPtr lpBaseAddress,
   IntPtr lpBuffer,
   uint cbRead,
   IntPtr lpNumberOfBytesRead
);

Microsoft documentation: Link