The spyglass and binoculars are, basically, a prop by any other name. However, when the player zooms in with them equipped (by pressing the assigned zoom button), it has a binocular/spyglass HUD. Also, if possible, it would show the distance to wherever the player is looking.
This would ideally be paired with a toggleZoom script, where the binoculars/spyglass are the only things that allow players to zoom. Weapons could also be scripted to allow zooming if this script is enabled.