A security apparatus for securing a portable electronic device to an immovable object includes a locking head having a base and a compressible element supported by the base. The locking head is adjustable between an unlocked configuration, in which the compressible element is uncompressed and insertable into and removable from an opening of the portable electronic device, and a locked configuration, in which the compressible element is compressed and secured within the opening of the portable electronic device.