Getting position in distance

I want to make a part in distance of my head like this


image
where:
Red is position i want to get
Green is distance
How can i make it?

local position = HeadCFrame:PointToWorldSpace(Vector3.new(0,0,-depth and its will be magnitude))

local Position = Head.CFrame.LookVector * (-Distance)

anyone know how to make it of camera? just replace Head CFrame to camera CFrame?

local position = workspace.CurrentCamera.CFrame:PointToWorldSpace(Vector3.new(0,0,-depth and its will be magnitude))