put out feelers

Examples from literature

It has two little "shells," two eyes, legs, and feelers. 
It will be noted that the spider has four pairs of legs and no feelers, whereas the ant has three pairs of legs and a pair of feelers. 
The head is remarkable for its large globular compound eyes, its short bristle-like feelers, and its very strong mandibles which bite up the bodies of the victims. 
They grow from six to twelve inches long and a couple of inches wide, with legs or feelers all along their sides, like the teeth of a pocket-comb. 
This hideous and loathsome-looking animal had projecting eyes that seemed to glare at one, very long and flexible antennae or feelers, and gigantic claws. 

feeler | American Dictionary

feeler
noun[ Cusually pl ]
us/ˈfi·lər/
one of the two long parts on an insect’s head that it uses to touch things

Examples of feeler

feeler
Particularly, in addition to the difficulty of making a perfectly conical shape for smaller feelers, the influence of surface unevenness on the feelers' dimensions increases.
If combined normal and shearing forces are applied to the sensing surface, the conical feelers make contact with the acrylic board and are subjected to compressive and shearing deformation.
I beg you, when this is all over, unless you have got a real winner, not to be tempted by any more of these feelers.
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