probes

in controlDict:

functions ( probes1 {
        type probes; functionObjectLibs ("libsampling.so");
        outputControl timeStep; // or every N iterations
        outputInterval 1;
        probeLocations (
            ( 0 0 0.1 )
            );
    fields ( U );  // fields to check.
    }
);


This could be interesting; it may replace sample.  Sample needs reconstructPar before use:  time-consuming.
This might not.