You want something like this...
autocam off
hide mouse
make object box 1, -50.0, -10.0, -50.0
sync rate 60
do
xMouseMove# = mousemovex()
yMouseMove# = mousemovey()
inc xCameraAngle#, yMouseMove# / 5.0
inc yCameraAngle#, xMouseMove# / 5.0
if xCameraAngle# < -85.0 then xCameraAngle# = -85.0
if xCameraAngle# > 90.0 then xCameraAngle# = 90.0
rotate camera xCameraAngle#, yCameraAngle#, 0.0
circle screen width() / 2, screen height() / 2, 2
position mouse screen width() / 2, screen height() / 2
loop
-= Out here in the fields, I fight for my meals =-