This is the one I bought. Costs $10.
Bike Mount, IPOW Universal Cell Phone Bicycle Rack Handlebar & Motorcycle Holder Cradle Compatible with iPhone 12/11 Pro Max/X/XR/XS MAX/8/7 Plus, Samsung Galaxy S10/S10e/S9, Nexus, HTC, LG https://www.amazon.com/dp/B015C03SI8/ref=cm_sw_r_cp_api_glt_i_T497JD4M4JCQJJ5A80T1?_encoding=UTF8&psc=1
https://www.amazon.com/gp/product/B015C03SI8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
I use one of these. I have an older push cart that doesn't come with the fancy attachments. I love it, other than I have to position it correctly or my volume buttons will be pressed, changing my volume. Its nice if you use a golf course app, or just wanna keep an eye on texts/emails and not have to carry it in your pocket. Good for music too.
Cell mount(don't let it distract you): https://www.amazon.com/Universal-Bicycle-Handlebar-Motorcycle-BlackBerry/dp/B015C03SI8/ref=sr_1_1?s=outdoor-recreation&ie=UTF8&qid=1468274577&sr=1-1&refinements=p_72%3A1248957011
Choices for rack trunks and/or panniers
timbuk2(highly advise you look into it): https://www.amazon.com/dp/B00R936DOS/ref=twister_B00B3XWZD8?_encoding=UTF8&psc=1
Hardbox(rack trunk, used to own one, very nice and good for clothing and light gear): https://www.amazon.com/M-Wave-122461-Amsterdam-Hard-Box/dp/B001EVAYFK/ref=sr_1_13?s=outdoor-recreation&ie=UTF8&qid=1468274731&sr=1-13&refinements=p_72%3A1248957011%2Cp_n_feature_keywords_two_browse-bin%3A6035256011
Affordable rack trunk: https://www.amazon.com/Bicycle-Roswheel-Trunk-Handbag-Pannier/dp/B008S4SX5E/ref=sr_1_2?s=outdoor-recreation&ie=UTF8&qid=1468274753&sr=1-2&refinements=p_72%3A1248957011
Or if you already have a backback you can go for the oldschool option(i.e. mil crate with zip ties):
Milk Crate: https://www.amazon.com/dp/B0001ACQQA/ref=twister_B002BDTFP0?_encoding=UTF8&psc=1
All of these items should have amazon free shipping(two days for prime, 6-8 for non prime members but still free)
Works like a charm. Doesn't budge. The straps hold it in place. Phone is totally accessible.
I'm not saying the routes are good the way they are - but I've always expected the lane to end when it ends rather than become lost. I also use one of these if i'm going someplace I haven't been. I do the same in my car when traveling to unfamiliar destinations.