They just planted explosives inside pagers and walkie-talkies, which were later purchased by Hezbollah. The effectiveness of such attacks is questionable; who the hell uses pagers and walkie-talkies? And in general, no one carries gadgets they got from work due to the risk of being monitored by their boss. But of course, it looks impressive to the press, and Lebanon is promoting this narrative to present itself as a victim.
In reality, most of this stuff either exploded in warehouses or didn’t explode at all.