keep/have an/your ear to the ground

keep an ear to the ground

 and have an ear to the ground; keep one's ear to the ground; have one's ear to the ground
Fig. to devote attention to watching or listening for clues as to what is going to happen. John had his ear to the ground, hoping to find out about new ideas in computers. His boss told him to keep his ear to the ground so that he'd be the first to know of a new idea.
See also: ear, ground, keep

keep your ear to the ground

or

have your ear to the ground

mainly BRITISH
If you keep your ear to the ground or have your ear to the ground, you make an effort to be aware of what is happening around you. Keep your ear to the ground. Know who is coming and who is going: a new vacancy could be an opportunity for you. Paul had his ear to the ground and always knew about future concerts before anyone else Note: In films, Native Americans used to be shown tracking people or animals by listening carefully to the ground for the sound of their footsteps.
See also: ear, ground, keep

have (or keep) an ear to the ground

be well informed about events and trends.
The idea behind this phrase is that by putting your ear against the ground you would be able to hear approaching footsteps.
See also: ear, ground, have

keep/have an/your ear (close) to the ˈground

(try to) be well-informed about what is or will be happening: Jane keeps her ear pretty close to the ground and can usually tell you what the mood of the staff is.
See also: ear, ground, have, keep