Sap, I can't find a Lake Baveno. There is a town of Baveno on Lake Maggiore. I guess that is where you mean.
What method of transport do you want to use? Car, train, boat?
And to where in Switzerland? It is a whole country!
The good news is that Baveno (the town) is on one of the two main rail lines from Milan north to Switzerland, so trains are an option.
Possibilities are:
1) The far end of Lake Maggiore is in Switzerland. You could take a lake boat to the other end of the lake, for example to Locarno.
Boat company website here: https://www.navigazionelaghi.it/
You could spend the whole day in Locarno, or take a local train to Bellinzona, a World Heritage site with THREE castles.
2) Train north to Domodossola, then the Domodossola-Locarno railway, a scenic route.
Website: http://www.centovalli.ch/en/railway/centovalli-railway/
3) Train north, through the Simplon tunnel, to Brig. 2 hours, limited trains.
Look up times on the SBB website: https://www.sbb.ch/en
Any further into Switzerland would take too, long for a day trip.