A device for detecting and/or monitoring optically invisible objects, such as underground pipes, warning systems or bodies buried in the ground or embedded in civil engineering works, this device being intended to be mounted on said objects and disposed substantially parallel to the general direction of said objects, this device including: - at least one electrically or optically conductive linear element, the at least one linear element extending longitudinally, - an insulating sheath covering the at least one linear element, the insulating sheath including at least one first face intended to be mounted on said objects and at least one second face opposite to the first face, the first and second faces (5, 6) being substantially parallel, the first face extending substantially in a plane and including a first substantially flat portion, the second face comprising a second substantially flat portion substantially parallel to the first substantially flat portion, - first gripping means formed on the first face of the insulating sheath and arranged to cooperate with the outer surface of said objects, the device characterized in that the first gripping means comprise a first series of longitudinal ridges and a second series of longitudinal ridges disposed respectively on either side of the first substantially flat portion, the first and second series of longitudinal ridges belonging to the first gripping means being formed respectively in the proximity of the lateral edges of the insulating sheath, and - second gripping means formed on the second face of the insulating sheath, the second gripping means including a first series of longitudinal ridges and a second series of longitudinal ridges disposed respectively on either side of the second substantially flat portion, the first and second series of longitudinal ridges belonging to the second gripping means being formed respectively in the proximity of the lateral edges of the insulating sheath. - at least one electrically or optically conductive linear element, the at least one linear element extending longitudinally, - an insulating sheath covering the at least one linear element, the insulating sheath including at least one first face intended to be mounted on said objects and at least one second face opposite to the first face, the first and second faces (5, 6) being substantially parallel, the first face extending substantially in a plane and including a first substantially flat portion, the second face comprising a second substantially flat portion substantially parallel to the first substantially flat portion, - first gripping means formed on the first face of the insulating sheath and arranged to cooperate with the outer surface of said objects, the device characterized in that the first gripping means comprise a first series of longitudinal ridges and a second series of longitudinal ridges disposed respectively on either side of the first substantially flat portion, the first and second series of longitudinal ridges belonging to the first gripping means being formed respectively in the proximity of the lateral edges of the insulating sheath, and - second gripping means formed on the second face of the insulating sheath, the second gripping means including a first series of longitudinal ridges and a second series of longitudinal ridges disposed respectively on either side of the second substantially flat portion, the first and second series of longitudinal ridges belonging to the second gripping means being formed respectively in the proximity of the lateral edges of the insulating sheath.