@Shf is right in that you should be using readAllStandardOutput. However, you're using the function execute() which is a static method. You should be calling start( ) from an instance of a QProcess.
It may also be a good idea to then either wait for the data with waitForReadyRead, or just wait for the process to finish with waitForFinished( ).
Also, there's an overloaded start function, which allows you to pass the whole command in, which may make your code easier to read: -
QProcess pingProcess;
QString exe = "snmpget -v 2c -c public 10.18.32.52 .1.3.6.1.4.1.30966.1.2.1.1.1.5.10";
pingProcess.start(exe);
pingProcess.waitForFinished();
QString output(pingProcess.readAllOutput());
Note that calling waitForFinished will hang the current process, so if you're going to do something that will take a while, you would then want to dynamically create the QProcess and connect to the finished() signal in order for a connected slot to then read the data.