Bricks 1.4 introduces the echo tag to render the output of any PHP function:
{echo:my_custom_function} – Echoes the value of the PHP function my_custom_function()
It accepts arguments, with or without single quotes, like so: {echo:get_the_date('Y-m-d', 55)} – Echoes the date of the post 55 formatted to Y-m-d
Please note that the echo tag does not support double quotes and the custom PHP function should return the value (do not echo the value inside of the custom function).