D-D fusion must emit certain particles, and likewise D-T and T-T. To date nobody has run an experiment using readily available particle spectrometers. There have been a few half-hearted measurements of induced activity, but no “real” measurements.
If you consider "track etch" dosimetry an "available particle spectrometer", then it's been done (and with positive results).
Well of course!
That’s what we need the flux capacitor for!