packageName = $ARGS[1];
if (packageName == null) return "package name not provided to script";
for (s : $node->softwarePackages) {
  if (s->name == packageName) {
    return s->version;
  }
}

Then create a script DCI with metric e.g.:

getPackageVersion("curl")

The script is using information about packages collected during configuration poll, so it will provide a value even if the agent is not available at the moment.