逆探知[gyakutanchi] phone trace
金属探知機[kinzokutanchiki] metal detector
金探し[kinsagashi] searching for gold
厳探[gentan] strict search
伺い探る[ukagaisaguru] to spy out

私立探偵[shiritsutantei] private detective
手探り[tesaguri] fumbling
人探し[hitosagashi] searching for someone
あら探し[arasagashi] finding fault
探し求める[sagashimotomeru] to search for

運針[unshin] handling the needle
検針[kenshin] inspection of a meter
絹針[kinubari] needle for silkwork
行動方針[koudouhoushin] course of action
指針[shishin] needle (of a compass, etc.)

自主指針[jishushishin] independent guideline
畳針[tatamibari] tatami needle
針鰻[hariunagi] elver (type of eel)
針金[harigane] wire