From Longman Dictionary of Contemporary Englishwatch somebody like a hawkwatch somebody like a hawkLOOK ATto watch someone very carefully → hawk
Examples from the Corpus
watch somebody like a hawk• He seemed to be watching her like a hawk, waiting for some reaction.• Today, more than usual, he had been watching them like a hawk.• Kruger is watching them like a hawk!• They're watching me like hawks here.• Parents should watch their kids like a hawk for sunburns.• And it's putting me off, having you watching me like a hawk all the time. 